Can std::array be Default-Initialized?

By declaring a variable as std::array x;, you can guarantee that all its elements will be default-initialized. According to the C 11 language standard (§8.5/11), any object without an explicit initializer is default-initialized.

However, you should be aware that default initialization has no effect on non-class, non-array types (§8.5/6), leaving their values indeterminate. For example, a default-initialized array of such types will have indeterminate values.

Value-Initialization of Arrays

If you wish to initialize all array elements to a specific value T{}, this is not default-initialization but value-initialization (8.5/7). You can value-initialize arrays easily in C 11 by using empty initializers:

int plain_int{};
int c_style_array[13]{};
std::array cxx_style_array{};

This will value-initialize all array elements, resulting in a consistent value of 0 for integers and the default values for their respective data types.